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Quick Overview
There are a few common reasons why a gas fireplace won’t light even though the pilot light is on:
- Dirty or clogged burner ports
- Faulty thermocouple
- Gas valve not opening fully
- Weak/improperly adjusted pilot flame
- Defective ignitor or ignition module
The pilot light provides a small flame that ignites the main burner when you turn on your fireplace. If this small flame is present but the main burner won’t light, it typically points to an issue with gas flow or ignition, not the pilot light itself. Some troubleshooting and cleaning of key fireplace components like the burner and thermocouple can often resolve the problem.
What is a Pilot Light?
The pilot light is a small flame that is always lit in a gas fireplace. It serves a couple of key purposes:
- Ignites the main burner – When you turn on your gas fireplace, the pilot light ignites the gas flowing from the main burner.
- Proves combustion airflow – The pilot light being lit proves there is proper ventilation for combustion gases.
- Operates the thermocouple – The pilot flame heats the thermocouple which sends a signal to the gas valve to open and allow gas flow.
The pilot light provides a constant heat source to trigger the thermocouple and gas valve to open when you want to use your fireplace. If it goes out, you will need to manually relight it before using your gas fireplace.
Pilot Light Components
- Pilot Burner – Small tube that the pilot flame comes out of.
- Thermocouple – Sensor next to the pilot burner that heats up and signals the gas valve to open.
- Ignitor – Typically a push-button ignitor that creates a spark to initially light the pilot.
- Pilot Gas Line – Fuel line bringing gas to the pilot burner.
These components all work together to keep the pilot lit and open the main gas valve when you want to use your fireplace. If any are damaged or dirty, it can prevent the pilot from igniting the main burner.
Why Won’t the Main Burner Ignite?
If you have a standing pilot that won’t properly ignite the main burner, there are several potential causes to check:
Dirty or Clogged Burner Ports
The main burner has a series of small ports where gas fuel exits and ignites. These ports can become blocked with debris, spider webs, dust, and lint over time. This prevents the gas from flowing out evenly and igniting.
Cleaning the burner ports with compressed air, soap and water, or a pipe cleaner can often resolve this issue. Make sure the burner is completely dry before attempting to relight after cleaning.
Faulty Thermocouple
The thermocouple is a heat-sensitive device that sits next to the pilot light. When it heats up, it sends a millivolt signal to the gas valve telling it to open and allow gas to flow.
If the thermocouple is defective or worn out, it won’t send the proper signal to the valve even though the pilot is lit. A simple thermocouple replacement is usually all that’s needed to resolve this.
Gas Valve Not Opening Fully
The gas valve has an internal solenoid that opens when the thermocouple sends it a signal. If this solenoid is faulty or weak, it may not be opening the valve 100% even with the pilot lit. This results in a low gas flow that won’t ignite the burner.
The valve may need to be repaired or replaced if cleaning the ports and thermocouple replacement doesn’t help. This generally requires a professional gas technician.
Weak Pilot Flame
For proper ignition, the pilot light must be adjusted to provide a strong enough flame. A weak flame that is too low or blowing to the side won’t ignite the burner reliably.
The pilot light may need adjustment to provide a taller, stronger flame pointed at the thermocouple and burners. Refer to your owner’s manual or contact a professional to adjust pilot light properly.
Defective Ignitor or Ignition Module
Most gas fireplaces have either a manual ignitor button or electronic ignition module that creates a spark to initially light the pilot. If these components are defective, the pilot may fail to ignite.
Check that the ignitor is sparking properly when pressed or that the ignition module is sending a spark signal when powered on. These ignitors are often inexpensive and easy to replace.
Steps for Troubleshooting
Follow these key troubleshooting steps if your gas fireplace won’t properly ignite with the pilot lit:
- Clean the Burners – Remove debris/dirt from ports
- Inspect the Pilot Flame – Ensure it is strong and aimed correctly
- Replace Thermocouple – Confirm it is generating proper voltage
- Test Gas Valve – Verify it is opening fully
- Check Ignitor – Confirm sparking and signal
- Professional Service – If needed for further inspection and repairs
Going through these steps methodically can often identify the underlying issue and get your fireplace lighting properly again.
Preventative Maintenance
You can help avoid issues with your pilot light and gas fireplace by following some simple maintenance practices:
- Clean the burners and pilot assembly annually.
- Visually inspect the pilot flame monthly.
- Replace the thermocouple every 2-3 years.
- Have gas fireplace professionally inspected yearly.
- Turn off pilot light during long periods of non-use.
Keeping your fireplace clean and well-maintained will minimize the chances of the pilot not igniting the burner properly. Always refer to the manufacturer’s recommendations as well.
When to Call for Service
If you’ve tried the troubleshooting steps above and your pilot still won’t properly ignite the main burner, it’s a good idea to call for professional service. A technician can fully evaluate the valve, thermocouple, control module and other gas fireplace components to pinpoint the exact cause.
They can also safely inspect gas connections, fuel piping and combustion airflow. Attempting to repair gas valves, piping or extensive cleaning is best left to qualified professionals. The cost for repairs will often be less than replacing the entire gas fireplace.
Conclusion
A standing pilot that won’t ignite the main gas burner is most often caused by a thermocouple issue, gas flow problem, or minor dirt buildup. Following some troubleshooting and preventative maintenance steps can typically get your fireplace lighting properly again. For any situation where the pilot or burner will not stay lit, immediately call a professional for assessment. Repairing issues promptly can restore full function and prevent bigger problems down the road. With some attention and care, your gas fireplace pilot and ignition system can provide trouble-free operation for years.
Frequently Asked Questions
Why does my gas fireplace make a clicking sound but won’t light?
A clicking sound usually means the ignitor or ignition module is sparking to light the pilot but gas is not flowing. This is typically caused by a pilot valve that has closed or a thermocouple problem not signalling the valve to open.
Why does the pilot keep going out on my gas fireplace?
The pilot flame extinguishing is most commonly caused by a weak flame, problematic thermocouple, or issues with poor combustion air flow. Inconsistent pilot flames that keep going out indicate a component needs repair or replacement.
Can a pilot generator cause issues with ignition?
Yes, a faulty pilot generator that is not producing the correct millivolt signal can prevent the gas valve from opening properly. This will lead to lighting issues with both the pilot and main burner.
What happens if my pilot light keeps burning?
If the pilot runs constantly, it will waste gas which leads to higher usage bills. It also risks sooting within the fireplace over time which requires excessive cleaning. The valve or gas control should be adjusted or repaired to eliminate the always-on pilot.
Why does my gas fireplace have orange flames?
Orange flames, especially when accompanied by smoke or soot, indicate incomplete combustion. This is usually caused by issues like debris clogging the burner, insufficient air flow, or problems with the gas regulator.
Gas Fireplace Ignition Troubleshooting Table
| Problem | Potential Causes | Solutions |
|---|---|---|
| Pilot won’t stay lit | Weak pilot flame, defective thermocouple, reversed gas line connection, poor gas line pressure | Adjust and inspect pilot hood, replace thermocouple, correct line connections, check line pressure |
| Pilot won’t light | Ignitor not sparking, no gas flow, electronic ignition module defective | Check/replace ignitor battery, confirm pilot gas valve is open, replace module |
| Main burner won’t light | Thermocouple issue, gas valve blocked, electronic ignition module issue, wiring problems | Replace thermocouple, inspect/clean valve, check module and wires |
| Burners extinguish shortly after ignition | Low gas pressure, faulty thermopile, pilot hood blocking thermopile | Verify adequate gas line pressure, check thermopile for shorts, adjust pilot for clean burn |
| Fireplace shuts off during use | Pilot blows out, thermocouple malfunctioning, low gas pressure | Shield pilot, replace thermocouple, confirm gas line pressure |
| Burner flame is low or weak | Plugged burner orifice, low gas pressure | Check/clean burner orifice, verify gas line pressure |
Summary
Troubleshooting a gas fireplace pilot that results in the main burner not lighting is often an easy process. In most cases, the pilot assembly just needs cleaning or the thermocouple requires replacement. Checking for clogs, proper gas pressure, and correctly adjusted components can reveal the issue.
Annual inspection and preventative maintenance will help minimize these ignition problems. In some cases where the gas valve, module, or piping are defective, professional service by an experienced technician will be required. Proper troubleshooting methods provide a safe way to get your gas fireplace lighting reliably again.